It could be a scene out of some apocalyptic movie, or an episode from Cormac McCarthy’s The Road – a man wearing a hoodie and carrying an enormous knife, wading through mud in an empty landscape. Your first instinct is to hide in a ditch until he goes past, but in fact, it’s one escaping member of a harvesting gang who have been out in the fields since six o’clock on a January morning, picking cabbages. Behind him rolls the rig, a complicated piece of machinery designed to enable hand-picked cabbages to be bagged up in the field, put on a lorry and on your supermarket shelf barely 48 hours later.

The rig, the cabbages and even the apocalyptic picker belong to Marshalls, a company that specialises in brassicas of every variety, and has been, since 2007, part of Produce World. This may sound like the vegetable equivalent of the Disney Experience, but is actually an unromantic hub processing vast quantities of veg, set in the flat, watery Lincolnshire countryside just outside Boston, the small market town whence the Pilgrims set off to the Netherlands in 1607, many of them leaving from there on the Mayflower for New England in 1620.

But at this time of year, it’s the brassicas that count and at Produce World the 5,000 acres of cauliflower, broccoli, brussels sprouts, green cabbage, savoy, spring greens, pointed cabbage, cavolo nero and purple sprouting broccoli are – almost uniquely in an industry full of blokes in wellies – under the care of the brunette, ‘not yet 30’ agronomy manager for Marshalls, Carolyn Coxe.

Today Coxe, who could not present more of a contrast to the knife-wielding hoodie out in the field had she elected to wear a Dior ball gown with her galoshes, is showing us January King, a heritage ‘stand alone’ cabbage destined for the shelves of Marks & Spencer. January King originated in France, and has three main varieties: Deadon, Marabelle and Noelle. Each variety ripens at a different time, and today it’s the turn of Noelle.

As everyone knows, 2012, a starry year for Olympic athletes, was an absolute shower – literally and metaphorically – when it came to fruit and veg. Whole harvests rotted in the rain from Scotland down to Cornwall, and the Lincolnshire fields were no exception. At the start of 2013 this fertile area that produces 60-70 per cent of all the veg grown in the UK is still partially under standing water and, even when the yellow winter sun breaks through the clouds, drips with moisture. ‘It was a bad year for all veg,’ Coxe says. ‘Too much rain and very low light levels during the summer. January King needs a good growing summer so it goes up a size in August and September and then gains more bulk in the winter. But last week a whole field of January Kings was under water – what has survived has been good, but we’re going to have to adapt better to weather extremes in the future.’ They would either have to find somewhere drier to operate, or breed plants that can cope with such dramatic weather.

Grab one while you can, therefore. Apart from anything else, a January King close up is extremely beautiful; the heart the rich purple colour of Victorian clerical vestments, encased in intricately detailed grey-green leaves, curled and fluted at the edges and veined with purple. Out in the field, Coxe, who has lost her voice but is still gamely sloshing through the mud to find a cabbage to photograph, explains that the ‘cabbage is actually a flower, and that the purpling occurs naturally when a cabbage is stressed [by temperature, too much water, cold] and produces anthocyanins. It will go dark green when you boil it,’ she adds. ‘To keep the purple colour, give it only a light steam.’

Produce World grows about 320,000 January King cabbages each season over 20 acres. That’s roughly 16,000 cabbages an acre. They are sown in glasshouses in April, planted out between the second week of May and early June, and harvested in January. Each one is picked by hand. ‘Six to eight people can pick 7,000 cabbages in a morning,’ Coxe says. ‘It’s very labour-intensive – one man using his eyes and a knife – and it’s very skilled work; difficult to do, and not much fun standing out in the field picking cabbages when the wind is whistling across from Skegness.’ Even so, many of the harvesting gangs are local men who have been picking for Produce World for 20 years, since they left school.

This particular part of the country is on silt, drained from fenland and about a metre below sea level. It’s criss-crossed by man-made dykes and dominated by the extraordinary tower of Boston’s 12th-century church, St Botolph’s, the largest parish church in England. ‘It’s a town famous for vegetables and the tower, which we call the Stump,’ says Lorraine Fountain, the category manager at Marshalls, ‘and we’ve got an ancient windmill too.’ Today, she has agreed to show us how versatile a cabbage can be by cooking a couple of January Kings for lunch.

‘Most people aren’t very adventurous with cabbage,’ she says, ‘but you can use them in all kinds of ways, not just with a roast – though they are the ideal accompaniment for that, especially pork. But juniper and caraway work well with cabbage too.’

Back in the kitchen of her 19th-century cottage in Boston, she conjures up three terrific cabbage dishes in the space of about 15 minutes. A soup with butter beans and cheese croutons; leeks, cabbage and bacon, and a prawn and cabbage stir-fry. They could not be simpler, or more delicious and – helpful at this time of year – are good for you, being high in antioxidants and low in calories.

January Kings are seasonal and will be available only until mid-February, when other brassicas will take over. Coxe is already planning the 2014 winter crop. She is hoping to grow flower sprouts, as well as the results of various on-going trials on veg such as kohlrabi, kale and chard. ‘We trial different varieties every year,’ she says. ‘Taste and appearance are the two most important things. But I do love the January Kings – it’s peaks and troughs all the time with them as they respond to everything, even moonlight – like cauliflowers, if it’s a full moon they carry on growing at night, so you have to keep a close eye on them. But it would be nice if they grew somewhere warmer.’